1. Field of the Invention
The present invention relates to a polarizing plate with a pressure-sensitive adhesive layer.
2. Description of the Related Art
In recent years, the thinning of an image display apparatus, in particular, an image display apparatus for mobile applications has been progressing, and hence there has been a growing requirement for the thinning of a polarizing plate to be used in the image display apparatus. A polarizing plate of the following construction has been proposed as a thin polarizing plate (for example, International Patent WO2009/069799A). A protective film for protecting a polarizing film is not arranged, and a pressure-sensitive adhesive layer is directly formed on the polarizing film so that the polarizing plate can be bonded to any other member.
Meanwhile, an improvement in functionality of the pressure-sensitive adhesive layer to be used in the bonding of the polarizing plate has been required. For example, a pressure-sensitive adhesive layer containing an ionic compound and having an antistatic function, and a pressure-sensitive adhesive layer containing a surfactant and having re-peelability have been known. However, a polarizing plate including a pressure-sensitive adhesive layer directly arranged on a polarizing film as described above involves a problem in that the polarizing film deteriorates owing to an additive in the pressure-sensitive adhesive layer. In addition, the polarizing plate including the pressure-sensitive adhesive layer directly arranged on the polarizing film involves a problem in that a substance in the polarizing film (such as iodine) contaminates any other member as an adherend.
A method involving arranging a protective film only on one side of a polarizing film depending on a pressure-sensitive adhesive to be used is conceivable as a method of solving the problems. However, when a polarizing plate of such construction is bonded to any other member, for example, the following problem occurs. As illustrated in FIG. 5, warping occurs to cause unnecessary peeling of the polarizing film and the protective film or appearance abnormality in an end portion of the polarizing film. Such phenomenon becomes a problem particularly in today's circumstances where an image display apparatus is frequently used under a severe environment (e.g., under high temperature and high humidity) in association with the diversification of environments where the apparatus is used including outdoor use of an image display apparatus for mobile applications.